6) Stephen and Tina have some stamps. After Stephen gives Tina 26 stamps, he has 40 stamps more than her. How many more stamps than Tina does Stephen have at first? (ans : 92)

7) Cheryl and Serene have some money. If cheryl gives Serene $20, they will have the same amount of money If Serene gives Cheryl $25, Cheryl will have twice as much money as Serene. How much money does Serene have?
(ans : $115)